Distribution and breeding sites of potential dengue vectors in and districts of

P. H. D. Kuslimawathie', R. R. M. L. R. Siyambalagoda' The Ceyloll JOllmal of Medical Science 2005; 48: 43-52

Abs tract DH F surveillance and control measures in these areas is an urgent need to reduce Entomological investigations were con­ morbidity and mortality, and the spatial ducted in 26 urban and semi urban areas in distribution of DF / DHF in U,e two districts. Kandy and Nuwara Eliya districts to Since, the breeding sites differed from one determine the distribution and breeding sites period of time to another and from one of potential vectors of dengue, viz., Aedes locality to another, dengue control measures aegypli Linnaeus and Aedes aibopicills shou ld be planned based on local and Skuse in these areas. Aedes larval surveys current entomological information. were carried out around suspected/ serologicall y positive dengue fever (DF)/ Key words: Ae. aegypti, Ae. a/bopicills, Kandy, dengue haemorrhagic fever (DHF) cases in Nuwara Eliya. dengue transmission areas, and, in bus depots, government institutions and tyre shops (high risk places for Aedes breeding) Intro ductio n in OF / DHF non transmission areas. Aedes aegypli Linnaeus is important as the primary vector of dengue fever (OF) and Aedes aegypli and Ae. a/bopictlls were not dengue haemorrhagic fever (DH F) in tropical encountered in the Nuwara Eliya town cOlmtries of the world. Aedes a/bopicllls Skuse (altitude 1900 111). Bu t, either Ae. a/bopiclllS or is considered as a secondary vector of DF in Ae. aegypti and Ae. a/bopictlls were South East Asia and the Western Pacific (1). encountered in all the o ther localities (eleva lion 100 -1300 m). The majority (96%) In Sri Lanka, OF was first reported in early of breeding sites of Ae. aegypli and Ae. 1960s (2). Since U,en, sporad ic, progressively aibopicills comprised of water storage large and more frequent OF / DHF outbreaks containers, discarded receptacles and occurred in the country. Over the past 10 tyres. Breeding sites of Ae. aegypli and Ae. years, the morbidity, mortality and the a/bopicills differed from one locality to spatial distribution of the disease increased another as welJ as from one time period to conSiderably with 15,434 suspected and anolher. serologically positive DF / DH F cases and 88 deaths for the year 2004. At present, OF / DHF This study shows that the areas situated is endemic in many urban and semi urban below 1300 111 elevation in Kandy and areas, and has invaded new areas, making Nuwara Eliya districts are receptive for the disease an important publiC health dengue transmission. Strengthening of OF / problem in U,e country (3).

J. ReglOllnl Office, Anli Mnlarin Cnmpnigll , No. 43/50, Tnlwalln, Knndy. 2. Director, Anti Malaria Ca mpaign Directorate, Nnrnhenpittl, 5. 44 P. H. D. KlIslllllawatilie, R. R. M. L. R. Siyambnlagoda

Occurrence of seasonal/periodic peaks of larval surveys. In DF/ DHF transmission DF /DHF in dengue endemic areas and areas in the districts, Aedes larval surveys emergence of new foci of transmission in were carried out around the suspected and hitherto OF /DHF transmission free areas are serologically positive DF / DHF cases that important problems faced by the dengue were notified mainly by the government control programme in the country. hospitals. In hitherto DF/DHF non Information on the distribution of Ae. aegypti transmission areas, the surveys were carried and Ae. aibopic/lls and their breeding sites in out in and around bus depots, government a particular area would definitely help to institutions and tyre shops (high risk plaies take timely and appropriate preventive and for Aedes breeding) as these institutions control measures to reduce the morbidity, reported frequent Ae. aegypti and Ae. mortality and the spatial distribution of the albopictlls breeding. During each survey, a disease. This study was carried out to minimum of 100 houses within a 200 m determine the distribution and breedingsites radius around the DF / DHF case or the high of Ae. aegypti and Ae. aibopic/lls in Kandy risk institution were visited, all possible and Nuwara Eliya . Aedes breeding sites were examined and 20 larvae from each positive container were Methods collected randomly by pipetting or dipping, Sludyarea depending on the nature of the breeding habitat. If a particular container had less This study was carried out from January2003 than 20 larvae, all larvae were collected. The to December 2004 in the Kandyand Nuwara larvae were placed in separate containers Eliya districts of Sri Lanka. The study area (one container per one habitat), staged and comprises of plain and hilly areas with a identified as 3,d and 4" stages using land area of 3,681 km' and an estimated mid standard keys (4, 5). The 1" and 2nd stage year population of 2.04 million, for the larvae were allowed to develop to 3'" and year 2004 (Chief Secretariat, Planning and 4"' stages, and the pupae to become adults Monitoring Division, Kandy). According to prior to identification. If, Ae. aegypti and/ or the Regional Epidemiologists in the Ae. aibopic/lls were not encountered in a Kandy and Nuwara Eliya districts, the particular area at the first survey, two more Kandy Municipality and the adjoining surveys at more than 3 month intervals were urbanized areas in the Divisional carried out in the same area. Aedes mosquito Director of Health Services (DDHS) areas, namely, Gangawatakorale, Harispattuwa, density was determined by the Container Kundasale, Pathadumbara, Udunuwara lndex (0 = percentage of containers positive and Yatinuwara are endemic for DF / DHF. for Ae. aegypti and Ae. albopictlls) for Ae. The has reported a few aegypti and lor Ae. albopictlls. mini outbreaks during the past few years. Breeding sites of Ae. aegypti and Ae. albopictlls were categorized int05 groups, viz., Entomological investigations carried out in (1) water storage containers (water storage the area cemented tanks and iron and plastic barrels), Twenty six urban and semi urban areas (2) discarded receptacles in the domestic and located at different altitudes in 24 DDHS peridomestic environment (discarded plastic areas in the Kandy and Nuwara Eliya containers, pots, bottles, coconut shells, districts were randomly selected for Aedes polythene, metal ware and tins), (3) tyres, Potential dengue vectors ill Knndy and Nffwara EUya 45

(4) domestic appliances (refrigerator trays, high CI values for Hasalaka (38%), Hatton flower vases and ant traps) and (5) others (11 %), Madawala (11 %), Pundaluoya (18%) (eg., bamboo stump, leafaxils, concrete slabs and (75%). High CI for Ae. and roof gutters). The relative importance of albopictlls, were observed in Hasalaka (25%), each category of containers for Ae. aegypti Madugoda (15%), Rikillagaskada (12%) and and Ae. albopictus breeding was determined Walapane (100%) (Table 4). based on the percentage positivity of each type of container for Ae. aegypti and Ae. Discussion albopictus breeding. Dengue and DHF is a disease complex caused by four serotypes of the dengue virus, Results namely, Dengue 1, 2, 3 and 4. The disease is Of the 26 study sites, neither Ae. aegypti nor transmitted by Ae. aegypti and Ae.albopiCtl/S Ae. albopictlls was encountered in the (1, 6, 7). Thus, natural transmission of Nuwara Eliya town. Ae. albopictus was DF/DHF depends on the presence of the encountered in Kalapitiya, Kurunduwatta, dengue virus, Aedes vector mosquitoes Hataraliyadda, Madugoda and Panwila. and a susceptible population. Both Ae. aegypti and Ae. albopictus were reported from the rest of the localities According to serological studies carried out (Fig 1). in Sri Lanka, the World Health Organisation (1985) reported DF in towns that are situated Ae. aegypti and Ae. albopictus were below an altitude of 1200 m (2). Vitarana encountered primarily in water storage (1986) too, reported that dengue was containers in Ambagamuwa, Bulugoho­ prevalent in areas below the altitude of 1000 tenna, Galagedera, Galaha, , m (8). However, these studies have not Hijjapura, Kandy, Madawala, Poojapitiya, sufficiently dealt with the entomological Rikillagaskada and Talatuoya; in discarded aspects of DF/DHF in these areas. In the receptacles in Daulagala, Hataraliyadda present study, Ae. aegypti and Ae. albopictus and Kalapitiya; and in tyres in Hangu­ were encountered even at elevations of 1300 ranketha, Hasalaka, Hatton, Madugoda, m, making the areas that are situated below Pundaluoya and Walapane (Table 1). 1300 m receptive for DF /DHF transmission. Also, the density of Ae. aegypti and Ae. In a particular area, the types of breeding albopictus remains high in some areas, sites of Ae. aegtjpti and Ae. albopictlls differ especially, Hasalaka, Hatton, Madugoda, from one period of time to another (Table 2). Pundaluoya, Rikillagaskada and Walapane, making these areas highly receptive for Water storage tanks are the most preferred DF / DHF transmission. Thus, strengthening breeding site of Ae. aegypti and Ae. albopictus of DF /DHF s urveillance and control while discarded receptacles and tyres serve measures, specially in urbanized areas as important breeding sites of the two vector situated below 1300 m elevation is of mosquito species (Table 3). importance in reducing morbidity, mortality and the spatial distribution of DF /DHF. In the study sites that were positive for Ae. aegypti and Ae. albopictus breeding, the In the absence of a specific treatment or a Cl for Ae. aegypti varied from 1 to 75%, with vaccine for DF /DHF, vector control is of 46 P. H. D. Kusllmnwalhie, R. R. M. L. R. Siyambalngoda

Map showing the study sites & occurrance of Ae. aegyp/i & Ae. a/bopictus In Kandy & Nuwara EUya Districts

N A

. ' . • • - Po0JlIPI a • • • • . r. ~ Wlla. r • • • . . ,-_".r . ' " , .... · • "" ..t·, . ,BuIb ahet,ona : . • • • " • • • ':.•. '" of • r- ". • .t~"Ic• M.lawala • • • • • • • • • • ••••• ••• ...... • . •' .••.•• ' . - . • . ..r?t ., • K..o\~!l • r* , • JJapur8 • • • • ...... • • , T,~,I)J", .:. • , • • • r.. " ,,'. , • DauiSSai \,-' .. •, • •• " .r * • •• ',Gal aha , •, •• ;ryampola r ~ apone" • , . • • • , • • • • " ." • • •• , • • , • • " • • .. , " • • • • • • • ...... " ,

•, • • • , • , , • • • • • ...... •

• Study Sites r Ae. albopiclus * Ae. CIEgypli

Figure 1 ;,0 Tablel. Number and % (given in parentheses) of different types of containers positive for Ae. aegypti and Ae. a/bopicus ~ --~ . in the study sites in Kandy and Nuwara Eliya districts: January 2003 - December 2004. -~ • "-~ oil- DDHSarea Locality Number (%) of containers positive for Ae. aegypti and Ae. a/bopichls in -~ 1< 5 different container types n "-~ WSC DR T DA 0 Total -~ . " ~ ~ Akurana Bulugohotenna 24 (83) 4 (14) 0(0) 1 (3) 0 (0) 29 (100) "- '"~ Ambagamuwa Ambagamuwa 7 (78) 2 (22) 0(0) o (0) 0 (0) 9 (100) s.. <: Calaha Calaha 5 (83) 1 (17) 0(0) o (0) 0 (0) 6 (100) - ~ Hanguranketha Hanguranketha 0 (0) o (0) 4 (100) o (0) 0 (0) 4 (100) "il tTl ~-. Hanguranketha Rikillagaskada 23 (55) 10 (24) 8 (19) o (0) 1 (2) 42 (100) ~ Hasalaka Hasalaka 0 (0) o (0) 6 (100) o (0) 0 (0) 6 (100) Hataraliyadda Hataraliyadda 2 (29) 5 (7l) o (0) o (0) 0 (0) 7 (100) Kotmale Kalapitiya 1 (25) 2 (50) 1 (25) o (0) 0 (0) 4 (100) Kotmale Pundaluoya 0 (0) o (0) 10 (100) o (0) 0 (0) 10 (100) Kundasale Kundasale 6 (35) 3 (18) 8 (47) o (0) 0 (0) 17 (100) Kurunduwatta Kurunduwatta 0 (0) 1 (33) 2 (67) o (0) 0 (0) 3 (100) Maskeliya Hatton 0 (0) 3 (17) 14 (78) 1 (5) 0 (0) 18 (l00) MCKandy Kandy 12 (53) 9 (39) 1 (4) o (0) 1 (4) 23 (100) Medadumbara Hijjapura 27 (96) 1 (4) 0 (0) o (0) 0 (0) 28 (100)

*WSC = water storage containers, DR =discarded receptacles, T = tyres, DA = domestic appliance, 0 =other (Co n/d. on next page) •

Table 1. (Contd.)

DDHSarea Locality Number (%) of containers positive for Ae. aegypli andAe. albopicllts in 5 different container types WSC DR T DA o Total

Nuwara Eliya Nuwara Eliya o (0) o (0) o (0) o (0) o (0) 0 (0) Panwila Panwila 1 (33) o (0) o (0) 1 (33) 1 (33) 3 (99) Pasbage 7 (30) 7 (30) 8 (35) 0 (0) 1 (5) 23 (100) Pathadumbara Madawala 23 (85) 3 (ll) 1 (4) 0 (0) 0 (0) 27 (100) Pathahewaheta Talatuoya 36 (80) 5 (ll) 0 (0) 1 (2) 3 (7) 45 (100) ." Poojapitiya Poojapitiya II (74) 2 (13) 0 (0) 2 (13) 0 (0) 15 (100) :I: Talawakele Talawakele 2 (40) 2 (40) 1 (20) (0) 0(0) 5 (100) <::l o :>< ~- Tumpane Calagedera 8 (67) 4 (33) 0 (0) 0(0) 0(0) 12 (100) - -" Udadumbara Madugoda 1 (4) o (0) 27 (96) 0(0) 0(0) 28 (100) ~ -".. Udapalatha Campola 14 (54) 7 (27) 2 (8) I (4) 2 (7) 26 (100) " Udunuwara Daulagala 2 (33) 4 (67) 0 (0) 0(0) 0(0) 6 (100) '" '" Walapane Walapane 0 (0) o (0) 3 (100) 0(0) 0(0) 3 (100) s: r-

V>'" 'WSC water storage containers, DR discarded receptacles, T tyres, DA domestic appliance, 0 other ~ . = = = = = ;: -if t •

Potential dengue vectors in Kandy and Nuwara Eliyn 49

Table 2. Number and % (given in parentheses) of different types of containers positive for Ae. aegypti and Ae. albopictus at different periods of time in three localities in Kandy and Nuwara Eliya districts: January 2003 - December 2004.

Study site Number (%) of containers positive for Ae. aegypti and Ae. albopic/us and date WSC DR T Other Total Bulugohotenna 2.1.2004 5 (71) 2 (29) 0 (0) 0 (0) 7 (100) 8.11.2004 9 (82) 2 (18) 0 (0) 0 (0) 11 (100) 10.12.2004 8 (100) 0 (0) 0 (0) 0 (0) 8 (100) Hijjapura 26.1.2004 38 (100) 0 (0) 0 (0) 0 (0) 38 (100) 21.2.2004 3 (100) 0 (0) 0 (0) 0 (0) 3 (100) 22.4.2004 5 (83) 1 (17) 0 (0) 0 (0) 6 (100) 22.10.2004 6 (100) 0 (0) 0 (0) 0 (0) 6 (100) Selambridge 7.1.2004 4 (36) 2 (18) 5 (46) 0 (0) 11 (100) 4.2.2004 0 (0) 3 (100) 0 (0) 0 (0) 3 (100) 11.5.2004 3 (50) 2 (33) 0 (0) 1 (17) 6 (100)

'WSC =water storage containers, DR =discarded receptacles, T = tyres, 0 =other

Table 3. Positivity of different types of breeding sites for Ae. aegypli and Ae. albopic/us in Kandy and Nuwara Eliya districts: January 2003 - December 2004.

Habitat Number (%) of habitats positive for

Ae. aegyp/i Ae. albopic/lis Total'

Water storage containers 126 (62) 108 (48) 214 (54) Discarded receptacles 25 (12) 53 (23) 75 (19) Tyres 48 (24) 52 (23) 94 (23) Domestic appliances 4 (1) 5 (2) 7 (2) Other 1 (1) 8 (4) 9 (2) Total 204 (100) 226 (100) 399 (100)

*Total number of containers positive for both Ae. aegyp/i and Ae. albopic/us breeding does not equal to the sum of positive containers for Ae. aegypti and Ae. albopic/us due to mixed breeding of the two species in 31 containers. 50 P. H. D. Ku swnawnthie, R. R. M . L. R. 5iyamoolagoda

Table 4. Container index (0) of Ae. aegypti and Ae. albopictus in different study sites in Kandy and Nuwara Eliya districts: January 2003 - December 2004.

DDHSarea Locality No.of containers No (%) of containers positive for encountered Ae. aegypti Ae. albopictus

Akurana Bulugohotenna 349 22 (6) 9 (3) Ambagamuwa Ambagamuwa 75 5 (7) 4 (5) Galaha Galaha 88 3 (3) 3 (3) Hanguranketha Hanguranketha 95 1 (1) 3 (3) Hanguranketha Rikillagaskada 279 8 (3) 34 (12) Hasalaka Hasalaka 8 3 (38) 2 (25) Hataraliyadda Hataraliyadda 129 o (0) 7 (5) Kotmale Kalapitiya 56 o (0) 4 (7) Kotmale Pundaluoya 39 7 (18) 3 (8) Kundasale Kundasale 234 12 (5) 5 (2) Kurunduwatta KlIrundllwatta 96 o (0) 3 (3) Maskeliya Hatton 126 14 (11) 3 (2) MC Kandy Kandy 376 18 (5) 7 (2) Medadumbara Hijjapura 441 40 (9) 15 (3) NlIwara Eliya NlIwara Eliya 186 0 (0) 0 (0) Panwila Panwila 70 0 (0) 3 (4) Pasbage Nawalapitiya 466 10 (2) 13 (3) Pathadumbara Madawala 149 17 (11) 10 (7) Pathahewaheta Talatuoya 272 18 (7) 25 (9) Poojapitiya Poojapitiya 133 4 (3) 11 (8) Talawakele Talawakele 100 4 (4) 1 (1) TlImpane Galagedera 191 4 (2) 8 (4) Udadllmbara Madllgoda 175 0 (0) 27 (15) Udapalath Gampola 393 8 (2) 19 (5) Udunllwara Daulagala 166 3 (2) 3 (2) Walapane Walapane 4 3 (75) 4 (100)

Total 4696 204 (4) 226 (5) •

Potentinl detlgue vectors in Knndy and Nuwarn E/iya 51 importance in DF/DHF prevention and Acknowledgements control where elimination of breeding sites The authors wish to thank Dr. L. B. H. of and is a priority. Ae. aegypti Ae. a/bopict"s Denuwara, the Deputy Provincial Director Although Ae. aegypti and Ae. a/bopict"s breed of Health Services, Kandy, for the support in a wide variety of containers, the most given for the field activities of the study. preferred breeding sites of these vectors in The Entomological Assistant, Mr. M. M. the study sites were the water storage Raafi helped in entomological investigations, containers (cemented tanks and iron and and Mrs. Swarna Seneviratne (Staff plastic barrels), tyres and discarded TecluUcal Officer) and Mrs. Nimali Piyatissa receptacles. Water storage is a common (Technical Officer), Department of household practice in the study sites, even Geography, Uruversity of Peradeniya, helped in the sites that are situa ted in the wet zone. in the preparation of the map. We thank them Water storage tanks were reported as too for their kind assistance. important breeding sites of Ae. aegypti and Ae. a/bopict"s in other localities of Sri Lanka References (9, 10), in other South East Asian countries (11 , 12) and in the Western Pacific (5). Thus, 1. World Health Organization. Chemical suitable measures have to be taken for methods for the control of vectors and elimination of vector breeding in these pests of public health importance. In: containers, if OF is to be controlled. Chavasse D.C, Yap H .H, eds. WHO/ CTD/ WHOPES/ 97.2, 1997; 16. In the study area, the types of vector breeding 2. World Health Organization. Arthropod sites differ from one time period to another -borne and rodent-borne viral diseases. and from one locality to another. Hence, OF / Report of a WHO Scientific Group, DHF control measures should be planned Technical Report Series, 719, Geneva. based on local and current entomolOgical 1985; 32. information, targeting the potential breeding 3. Ministry of Health, Sri Lanka. Frame­ sites of Ae. aegypti and Ae. a/bopict"s in the work for plan of action for prevention particular areas, in order to achieve effective and control of dengue fever in Sri Lanka. and efficien t OF / 0 H F con trol. Draft prepared by the Epidemiology Unit, Minis try of Health, Colombo. Ae. aegypti and Ae. a/bopict"s were not 2005; 1-24. encountered in the Nuwara Eliya town 4. Barraud P.). The fauna of British India, (elevation 1900 m) in the present study. With Vol V. London, Taylor and Francis. the global warming, increase in temperature 1934; 138-143. and less rainfall is expected at high elevations in the Nuwara Eliya district (13). 5. World Health Organization. Guidelines for dengue surveillance and mosquito This may create suitable habitats for Ae. control. Western Pacific education in aegypti and Ae. a/bopict"s breeding at action Series No. 8, WHO Regional elevations higher than 1300 m. Thus, regular Office for the Western Pacific, Manila. and long term entomological inves tigations 1995; 5-15. in these areas would help to detect such areas early and to take timely remedial measures 6. Hapugoda M.D., Gunasekera M.B., de in order to prevent OF / DHF transmission Silva N.R., Gunasena 5., Prithimala LD., in these areas. Dayanath M.Y.D. and Abeyewickreme • •

52 P. H. D. Kusllmnwnthie, R. R. M. L. R. Siynmbalngoda

W. Detection of dengue virus in Aedes Lanka. Ceylon Journal of Medical a/bopictus mosquitoes by Reverse Science. 2003; 46: 51-60. Transcription Polymerase-Chain 10. Yapabandara A.M.G.M. and Abeykoon Reaction-Lipid Hybridization (RT-PCR­ LH) based assay. The Bulletin of the Sri A.R. Aedes aegypti and Ae. nlbopictus Lanka College of Microbiologists. 2003; breeding sites in the Municipal 1 (1): 30-31. Council area. Sri Lanka Association for the Advancement of Science, 7. Hapugoda G.P.G., de Silva N.R. and Proceedings of the 58th Annual Session, Abeyewickreme W. Breeding of Aedes 2002; 20. aegypti and Aedes albopictus in some dengue endemic areas. Sri Lanka 11. Manual on entomological surveillance College of Microbiologists, Annual of vector borne diseases, eds: Rahman Academic Sessions. 2000; Abstract no.4. S.J ., Sharma S.K., Rajagopal R. National Institute of Communicable Diseases. 8. Vitarana T., Herath P., Kalpage K., Ministry of Health and Family Welfare, Jayasekera N., Wickrarnasinghe M. and New Delhi, 1989; 82-89. Gunatilake V. Study of mosquito borne diseases In some new irrigation 12. Sharma S.K. Entomological investi­ schemes in Sri Lanka, with particular gations of a dengue fever outbreak: reference to filariasis and arbovirat experience from rural areas of Haryana, diseases. Proceedings of the workshop India. Dengue Bulletin. 1998; 22: 3&-39 . on irrigation and vector borne disease 13. Wijesundera M.de.S., Herath H.M. transmission. International Irrigation S.5.D., Rajapakse de Alwis R.w. Management Institute. 1986; 9-13. L.c., and Fernando H. M. Initial subsectoral 9. Kusumawathie P.H.D. and Fernando draft on national action plan on climate W.P. Breeding habitats of Aedes aegypti change and health - Sri Lanka. Ministry Linnaeus and Ae. albopictus Skuse in a of Forestry and Environment, Sri Lanka, dengue transmission area in Kandy, Sri 1998; 3-22.